Process of making prfssure sensitive record material



Patente pr. 25, 195i) National Sash Register Company, Dayton, Ohio, acorporation of ltziaryiand hlo Drawing.

@riginai application November 8,

1947, Seriai No. 784,939. Divided and this appiication December 2, 19

2 Glaims. i

This invention relates to improvements in process of making apressure-sensitive record material. This application is a division ofthe pending application of Barrett K. Green. Serial No. 784,939, filedNovember 8, 1947, for Process of making pressure-sensitive recordmaterial.

The principal object of this invention is to provide a process of makinga pressure-sensitive re ord material, on which a mark of dstinctivecolor may be produced by the mere application of localized pressure, andwhich is not subject to the disadvantages inherent in the pressure-senitive record material disclosed in United States Letters Patent No.2,299,593, patented October 20, 1942, on the application filed byBarrett K. Green on February 23, 1940. That patent dis closes apressure-sensitive record material including the combination of aninsulating medium, a rupturable solid material such as gum dammar,

having included therein interspersed droplets of a plurality of liquidreagents, which are chemically reactive to produce a distinctive colorin the record material at the points of application of localizedpressure thereto, such pressure rupturing the insulating medium topermit chemical reaction between the two liquid reagents. The tworeagents disclosed in this patent are gallic acid and ferric ammoniumsulphate, each dissolved in glycerine. These reagentsare ionized by theglycerine, which constitutes an ionizing medium, and the c emicareaction roceeds by oi ions when the two solutions are allowed to uponthe rupture of the insulating medium. The reaction disclosed in thatpatent depends upon the presence of the reagents in an ionizing medium.1

However. any availableionizing medium is hygroscopic, with the resultthat the record material, made in accordance with this patent, issensitive to an excess of moisture, and conditions oi high humidity maycause the insulating medium to cease to be eifective, with the resultthat the chemical reaction takes place without any application oflocalized pressure, and the record material is stained and discolored,so that it ceases to be useful.

As stated above, the principal object of the present invention is toprovide a process of making a pressure-sensitive record material that isnot subject to the defects and disadvantages of that disclosed in PatentNo. 2,299,693, as inclic'ated above.

Another object of the present invention is to provide a process ofmaking a record material upon which a mark of distinctive color mayproduced, at the point of application of localized Eerial No; 63,212

(Ci. Hi -36) pressure thereto, by such mere application of localizedpressure, and which will not become discolored or stained due to theeffect of light, atmospheric conditions, or aging.

In short, it is the object of this invention to provide a process ofmaking a pressure-sensitive record material in which the mark ofdistinctive color will be produced only at the points of application oflocalized pressure, and at no other points, and under no otherconditions.

Another object of this invention is to provide a process of making apressure-sensitive record material in which the mark of distinctivecolor is produced by the chemical reaction of color-forming reactants.in the absence of any liquid ionizing medium therefor.

A further object of this invention is to provide a process of making apressure sensitive record material in which a mark of distinctive coloris produced by a reaction between solid particles of color-formingreactants.

Further objects, and objects relating to details and economies ofoperation, will definitely a pear from the detailed description tofollow.

The objects of this inventon have been attained by the severalembodiments thereof described in detail in the following specification.This invention is clearly defined and pointed out in the appendedclaims.

In general, the present invention contemplates a process of making apressure-sensitive record material including the forming on a supportingmember a film-like deposit of solid particles of a plurality ofadsorption c'olor forming reactants disposed in contiguity with eachother, such reactants being so selected that they react, in the absenceof a liquid ionizing medium for the reactants, to form a distinctivecolor when brought into contact with each other, and a solid insulatingmedium insulating said reactants from color-forming reaction contactwith each other. Upon application of localized pressure to the rec- 0rdmaterial, as by drawing a stylus acros it, the insulating medium isruptured at the points of application of said localized pressure, andsuch rupture permits color-forming reaction contact between thereactants at such points, in the absence of any liquid ionizing mediumfor said re actants. The result is that a mark of distinctive color isproduced by the mere application of localized pressure.

color employed of the sc-cal led adsorption type wherein an inorganiccompound causes a color change in an organic compound coming intocontact therewith.

Of the reactant materials employed the organic material is an electrondonor aromatic compound having a double bond system which is convertibleto a more highly polarized conjugated form upon taking part in anelectron acceptor-donor solid surface chemical reaction, giving it adistinctive color. and the inorganic material is a material which is anacid relative to the organic material so as to be an electron acceptorwhen in adsorption contact therewith. Both materials are in fineparticle form in order to furnish a large reactant surface area per unitarea of the record material which enhances the depth or" color per unitarea of the record material.

According to one embodiment of the invention, solid particles of one ofthe color-forming reactants are carried by and dispersed in a solidinsulating medium, to which a coating of solid particles of anothercolor-forming reactant is applied. In this case, the application orlocalized pressure ruptures the solid insulating medium, at the pointsof application of such pressure, and brings about color-forming reactioncontact between the solid particles of color-iormin reactants at suchpoints, thus producing the mark of distinctive color. Preferably, thispressure-sensitive record material includes a base web, such as afibrous web of paper or the like to which the coating of solidinsulating medium and the color-forming reactants is applied.

The insulating medium is a pressure-rupturable film derived from anorganic film-forming hydrophilic colloid substance.

Since it is difiicult to show precisely the spatial relationship betweenthe solid par-holes or colorforming reactants, the solid insulatingmedium, and the base web, it is preferred not to attempt to illustrateany embodiment i this invention by drawings.

In the following examples, there will be described embodiments ol' thisinvendon, by means of which the objects of the invention have beensuccessfully attained.

An embodiment of this invention produces a material that comprises abase web of paper having applied thereto a coating including casein asthe solid insulating medium and two color-forming reactants; namely,kaolin and the compound 2,4-bis lp-lp-dimethylaminoplienylazoi aniiino]6-hydroxy sym. triazine, having the structure The pressure-sensitiverecord material made using these ingredients is normally yellow incolor, and the application of localized pressure thereto, as by drawinga stylus across the material, ruptures the solid insulating medium andpermits the solid particles of kaolin and the organic color-formingreactant to come into colorforming reaction contact with each other,producing a dark blue mark at the points of application of suchlocalized pressure. This record material is not affected by atmosphericmoisture and is relatively stable for a long period of time. Otherorganic film-forming hydrophilic colloid substances such as gelatin,starch, methyl cellulose, or polyvinyl alcohol may be substituted forcasein as the solid insulating medium in the rec- 0rd materialconstituting this embodiment of the invention. Attapulgite may besubstituted in this embodiment for the kaolin as the inorganic material,using gelatin or polyvinyl alcohol as the solid insulating medium.

One embodiment oI the invention for making a pressure-sensitive recordmaterial, using the ingredients above referred to, consists of thefollowing method: A slurry of kaolin and water was prepared including 50parts by weight of kaolin to 50 parts by weight of water and a minorproportion of a suitable dispersing agent, such as sodium metaphosphate.A 20% by weight solution of casein in water was made, to which parts byweight of a 28% ammonium hydroxide solution were added. The kaolinslurry and this alkaline casein solution were thoroughly mixed, in theratio by weight of kaolin to casein or" 10 to 1, and blended, and themixture was applied to the paper as a coating, which was dried thereon,after which the coated paper was calendered or treated in any desiredway to give the proper surface finish. A solution in toluene of about0.5% by weight 01' the organic color-iorming reactant above referred towas then applied to the coated side of the paper. The excess or thissolution was removed, and the treated paper was dried to evaporate thetoluene, alter which it was ready for use.

The casein constitutes the solid insulating medium, insulating one ofthe color-iorming reactants-that is, kaolin-iroln coior-forming reactioncontact with the other color-forming reactant--that is, the triazinecompound. Upon the application of localized pressure to the coatedpaper, as by drawing a stylus thereover, a dark; blue mark is producedat the points of application 01 such localized pressure. Suchapplication of pressure ruptures the solid insulatmg medium at thepoints of application of pressure, permitting color-forming reactioncontact between the solid particles oi kaolin and the solid particles ofthe triazine compound.

When the coating ingredients are applied to the paper, such coatingshould weigh about .0023 pound per square ioot of surlace and have athickness of the order of from .0005 to .001 inch. The thickness of thecoating varies, or course, with the treatment to which the recordmaterial is subjected in iinishing. The solid particles of kaolin inthis record material may be or about the order of ten microns indiameter, although considerable variation in particle size is possiblewithout any ill effects. Particle size of the triazine compound islargely determined by the method oi application of that ingredient. Theparticles of these reactants may be as large as ten microns in diameterand frequently are much smaller.

This record material has also been made usin gelatin as the solidinsulating medium and attapulgite as the inorganic color-formingreactant. In this case, a slurry of attapulgite and water was made,which was thoroughly mixed with a 20% by weight solution of gelatin. Theproportions of attapulgite and gelatin used should be such that, in thefinished coating, the weight of the gelatin will be about 20% of theweight of the attapulgite. The mixture of the attapulgiteslurry and thegelatin solution was applied to the paper as a coating, which was driedthereon.

Thereafter, a solution in toluene of about 0.5% by weight of the organiccolor-forming reactant was applied to the coated side of the paper. TheeX- cess of this solution was removed and the treated paper dried toevaporate the toluene, after which t it was ready for use. The sameprocedure was successfully used with a solution of polyvinyl alcoholsubstituted for the gelatin solution. The proportions of polyvinylalcohol and of attapulgite used were such that the finished coating hadattapulgite and polyvinyl alcohol therein in the ratio by weight of tol.

The pressure -sensitive record materials disclosed herein are notclaimed in this application but are disclosed and claimed in the pendingapplication of Barrett H. Green, Serial No. 784,- 938, filed November8,. 1e47, for Pressure senst tive record material, in a division of itSerial No. 59,423, filed November 10, 1948.

It is understood that the process of making a pressure-sensitive recordmaterial described herein is susceptible of considerable variationwithout departing from the spirit of the invention.

What is claimed is:

l. The process of making a pressure-sensitive record material includingthe forming on a supporting member a film-like deposit of solidparticles of a plurality of adsorption color-forming reactants disposedin contiguity with each other and a solid insulating medium, derivedfrom an organic film-forming hydrophilic colloid substance, insulatingsaid reactant particles from color-forming reaction with each other, atleast one of said reactants being an inorganic compound and at leastanother of the reactants being an organic compound adsorbable therewith,and said reactants being so selected as to react, in the absence of aliquid ionizing medium for the reactants, to form a distinctive colorwhen brought into adsorption contact with each other, one of thecolor-forming reactants bein the compound 2,4-bislp (pdimethylaminophenylazo) anilinol 6 hydroxy sym. triazine, having thestructure and the inorganic reactant being in fine particle formproviding a large adsorbent surface area and which is an acid relativeto the organic reactant so as to be an electron acceptor when inadsorption contact with said organic reactant.

2. The process of making a pressure-sensitive record material includingthe steps of coating a supporting member with a film of solid insulatingmaterial, derived from an organic film-forming hydrophilic colloidsubstance, having particles of a first color-forming solid reactantdispersed therein, and depositing on said film particles of a secondcolor-forming solid reactant, one of said reactants being an inorganiccompound and the other of said reactants being an organic compoundadsorbable therewith, and said reactants being so selected as to form adistinctive color when brought into adsorption contact with each other,and said solid insulating material being such as to insulate thereactants from colorforming reaction contact with each other, saidsecond color-forming reactant being the compound 2,4 bis [p pdimethylaminophenylazo) anilinol G-hydroxy sym. triazine, having thestructure REFERENCES CITED The following references are of record in thefile of this patent:

FOREIGN PATENTS Country Date Great Britain Jan. a, 194:3

Number

1. THE PROCESS OF MAKING A PRESSURE-SENSITIVE RECORD MATERIAL INCLUDINGTHE FORMING ON A SUPPORTING MEMBER A FILM-LIKE DEPOSIT OF SOLIDPARTICLES OF A PLURALITY OF ADSORPTION COLOR-FORMING REACTANTS DISPOSEDIN CONTIGUITY WITH EACH OTHER AND A SOLID INSULATING MEDIUM, DERVIEDFROM AN ORGANIC FILM-FORMING HYDROPHILIC COLLOID SUBSTANCE, INSULATINGSAID REACTANT PARTICLES FROM COLOR-FORMING REACTION WITH EACH OTHER, ATLEAST ONE OF SAID REACTANTS BEING AN IORGANIC COMPOUND AND AT LEASTANOTHER OF THE RECTANTS BEING AN ORGANIC COMPOUND ADSORBABLE THEREWITH,AND SAID REACTANTS BEING SO SELECTED AS TO REACT, IN THE ABSENCE OF ALIQUID IONIZING MEDIUM FOR THE REACTANTS, TO FORM A DISTINCTIVE COLORWHEN BROUGHT INTO ADSORPTION CONTACT WITH EACH OTHER, ONE OF THECOLOR-FROMING REACTANTS BEING THE COMPOUND2,4-BIS(P-(P-DIMETHYLAMINOPHENYLAZO)ANILINO) 6 HYDROXY SYM. TRIAZINE,HAVING THE STRUCTURE